Tuesday, August 27, 2013

An Amazing View of the Tropics

No, I'm not talking about crystal blue waters and sandy beaches. 

The tropical storm season in the Atlantic seems to be progressing in fits and starts this year.  So far there have been six named storms and none have been particularly noteworthy.  Note that NOAA's updated hurricane forecast in mid-August maintained a high probability for an active tropical season. It may be just a matter of time before the first major storm forms and occupies our attention. In the meantime, there are a couple of neat web sites and pages you may want to visit to get in that "tropical mood".

Here is a very cool image of 170 years of tropical cyclone tracks.

Image of tropical cyclone frequency. Credit: NOAA

This image comes to us from NOAA's Environmental Visualization Laboratory. The National Climatic Data Center (NCDC) put together a database of 11.967 tropical cyclones from 1842 to 2012. Early reports, prior to the use of weather satellites, came from ship reports. These were generally reliable reports. However, if you look at the vast expanse of ocean and the preferred shipping lanes, no doubt some storms occurred and were never detected. Now satellites can detect even the smallest disturbance over the oceans.

The Environmental Visualization Laboratory created this image from the storm tracks in the database. On the left is the eastern hemisphere image of the Atlantic Basin and the eastern Pacific, while on the left is the western hemisphere. The brighter the color, the more cyclone tracks overlapped. Note the very bright spots in the western hemisphere in the Bay of Bengal (India) and western Pacific.

Contrast the frequency image with the image below, a depiction of the cyclone intensity. The colors represent the maximum sustained wind speed over the course of a storm's life.

Image of tropical cyclone intensity.  Credit: NOAA
There is a greater spread of strong cyclones over thee northwestern Atlantic. That makes sense since many tropical storms can originate off the coast of Africa and intensity as they move west across the Atlantic.In the western hemisphere the more intense storms appear to occur near the Philippines.

NOAA has a really slick tropical storm track viewer that allows you to view tracks in the database. You can search for all tracks that have affected a particular location, or you can search on storm names, or for an ocean basin.

Storm tracks within 65 nm of Cape Hatteras, NC, 1842-2012. Credit: NOAA

This image is a search of a storm tracks within 65 nautical miles of Cape Hatteras. Looks like hurricane convergence! Along with the image, there is a data viewer on the left side which lists each storm. You can also mouse over any of the tracks and that storm will be highlighted in the list. You can then view more information on the storm.

When you search on a storm name, you get a list of storms with that name and the year they occurred. This is an image of the track of Hurricane Andrew in 1992. Mouse over any of the points on the map and the storm information for that point is highlighted in the left data window.

Storm track for Hurricane Andrew in 1992 using the Historical Storm Track viewer
If you are a tropical storm fan you can kill a lot of time on this web site.

Finally, NOAA's Ocean Today web site has a nice video on the Hurricane Hunters. This is the first time I've seen this web site and it has a lot of excellent videos and information on the ocean environment. Be sure to check it out.


Zach Cox said...

I wonder what is going on in the South Atlantic. Is there just not enough 'fetch' area to get something going?

Zach Cox said...

The Wikipedia article "http://en.wikipedia.org/wiki/Tropical_cyclogenesis"

Does a good job describing the South Atlantic. The article also has a global map similar to the one in this post.

Additionally the article points out why no tropical cyclones form in the South Eastern Pacific, Yhe Humbolt Current.

Steve Hilberg said...

Zach, dry air and strong upper level winds have kept a lid on this so far. However, that doesn't say anything about the next three months, so standby!

Steve Hilberg said...
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